


Awkward Beginnings to a Strange Relationship

by SpyroForLife



Series: ZaDR Week 3 [1]
Category: Invader Zim
Genre: Alien Biology, Awkward First Times, Explicit Sexual Content, Exposition, First Time, Grinding, Hand Jobs, M/M, Mating Cycles/In Heat, Older Dib (Invader Zim), Oral Sex, Pheromones, Premature Ejaculation, Riding, Xenophilia, ZADR Week Phase 3
Language: English
Status: Completed
Published: 2020-07-19
Updated: 2020-07-19
Packaged: 2021-03-04 19:55:26
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 13,615
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25381954
Author URL: https://archiveofourown.org/users/SpyroForLife/pseuds/SpyroForLife
Summary: Something weird's going on with Zim. And not his normal kind of weird. That purple discoloring on his face, the sweating, his shaking and other odd behavior... it all means something. And Dib's gonna find out what.
Relationships: Dib/Zim (Invader Zim)
Series: ZaDR Week 3 [1]
Series URL: https://archiveofourown.org/series/1838137
Comments: 22
Kudos: 203





	1. In Which Zim Is Acting Strange

**Notes for the Chapter:**

> This was written for ZaDR Week 3 on Tumblr! Details can be found here: https://spyroforlife.tumblr.com/post/622223971291643904/zadrweek3-all-forms-of-art-will-be-accepted
> 
> I plan on linking every prompt together into a consecutive storyline. Each prompt will have its own fic associated with it and all will be in a collection of their own making it easy to go from one to the next. This prompt is Awkward Beginnings and yes, this entire thing is just for that, I got a bit carried away. Enjoy!

It wasn't that Zim acting strange was new to Dib. He's known the alien for nearly six years now and still found the other's mannerisms and personality strange. During the time he's been here, Zim has become quite adept at acting human, picking up on slang and body language, even learning various hand gestures. Dib had fond memories of him repeatedly getting in trouble in middle school upon learning the utility of 'flipping the bird'. Though unfortunately for Zim, just using his pointer finger to innocently gesture to things also made particularly uptight teachers think he was being rude, so he still got in trouble for that too. It was funny to Dib, though.

Still, despite how much he's learned about humans, Zim was still quite odd. That interesting way he sometimes mixed up his grammar, making Dib theorize that was how irken sentences were laid out, and how he often inflected onto the wrong syllable when speaking dramatically. Those long, cocky strides he used everywhere he went as though he was marching. How he hissed when upset and sometimes even gestured aggressively with his claws at other students. The bizarre, hyper-specific questions he would ask teachers in class about Earth's military capabilities against various scenarios he thought up on the spot. His tendency to pick through whatever he got from the cafeteria meticulously, searching for anything edible, before proceeding to throw most of it out and snack on his own irken food, all of which looked like candy or snacks to the unknowing eye. Running off from class halfway through the day and not coming back until tomorrow. Sometimes he was simply absent from school altogether, often prompting Dib to have to go to his base or track him down to stop yet another plan to conquer Earth.

But Dib was used to all that. Zim's quirks were familiar and even endearing to him now after all this time and even having to stop his evil plans was more just a nuisance than truly scary or difficult for him. No, now Zim was beginning to act strange in a completely new way.

One day he was normal, bragging to Dib about something he was working on that would blow all his previous plans out of the water and would surely spell the downfall of the human race. The next, he was walking into their first period class more tense than Dib has ever seen him.

His brows immediately went up at the wary way Zim walked through the door, eyes darting around to check the location of every single student before he briskly made his way to his desk and sat down, grumbling something as he rummaged through his backpack for the homework from last night. When he extracted the paper, it snagged on something, and he gave a frustrated growl as he yanked it out. The paper came out with a large tear in it, the bottom corner dangling off by a thread. Zim let out a loud groan and slammed the paper onto his desk, before kicking the backpack, drawing concerned looks from the other students.

Dib snorted with amusement, wondering what had Zim so worked up. It wasn't uncommon for a plan to go wrong before Dib ever did anything, or for GIR to simply push Zim's buttons a little too hard, so this behavior didn't immediately tip Dib off that anything was out of the usual. It was how the rest of the day went that made him think something unusual was going on.

Zim spent the entire first class period fidgeting. Again, not entirely new. Zim was very energetic and he got bored very easily in these classes, having ranted to Dib before that he hated them but by this point he was determined to see them through and graduate high school like all the normal Earth spawn. With only a few months left, he wasn't quitting now. But said fidgeting usually consisted of little more than him drumming his fingers against his thighs or doodling swirls and complex patterns on stray bits of paper. This time, his entire body seemed to be shaking, and only a few minutes into the lesson, he slipped a small cube with various buttons out of his backpack.

Dib focused on it, trying to see what it was, but he was seated fairly far from Zim so it was hard to tell. Then the soft sound of clicking reached his ears as Zim repeatedly ran a thumb against one of the sides of the cube, staring vacantly at the teacher. A fidget cube. Zim was simply playing with a fidget cube.

Dib let out a breath he hadn't realized he was holding and looked back at the teacher too. Alright, so he had a new toy. Nothing to worry about. Dib sometimes used one to stim as well, though has been doing it less lately as classes got more difficult and thus kept him fairly engaged. Zim must have just seen his cube and wanted one for himself, the things were everywhere.

The clicking was a nice kind of background noise even from a distance. He wondered what Zim was thinking about. What had him so on edge today? Was he planning something? Or was he expecting a call from his leaders? Zim had told him before about something called “Probing Day” where the Tallest apparently contacted various high ranking military members, including the entire Invader class, to check their progress on their assignments. The punishment for not providing a satisfactory report was what Zim referred to as a “pummeling.” It sounded unpleasant and exactly the kind of bullshit he has come to expect from Zim's sadistic race. Maybe Zim had that on his schedule? Though he doubted it. Zim had complained last time about needing to call the Tallest himself as they had missed the window when they should have called him. Dib had just taken that as proof that his leaders didn't give a fuck about him but Zim refused to see it that way.

The teacher briefly stopped talking as she turned to the board to begin writing out a long equation, and Dib's eyes darted over to Zim as he turned his cube about a few times before settling on the side with a little switch, flicking it back and forth. This was fairly silent, and Zim seemed to swallow, his other hand shaking as he copied down the equation onto a sheet of paper. He began working on solving it the moment it was fully written.

Dib was so caught up in watching him that he didn't notice that the teacher was scanning the room for anyone not paying attention, before proceeding to call on him. “Mr. Membrane.”

Dib jolted and sat further upright, looking at her while a few of his classmates snickered. “Oh. Yeah?”

“Why don't you come up to the board and show us how you'd solve this equation?” She held the marker out expectantly.

Dib sighed and got up, resisting the urge to roll his eyes. She always did this sort of thing and it never worked out like she hoped. He examined the equation and then began writing.

Several lines down and he was giving the answer, underlining it a few times and then turning to her, holding the marker out wordlessly. Lips drawn into a thin line, she took the marker back. “That is correct. Thank you.”

He nodded and returned to his seat. He was only in this damn AP Calculus class because his dad insisted he get as many math credits as he could so it would be less for him to get through in college. Plus he could use it to boost his GPA. Dib didn't find it especially challenging, just tedious. He could tell his teacher was irritated by his casual proficiency, how he almost never spoke up in class on his own or offered to assist his fellow students, but always seemed one step ahead of her own knowledge. Even when she tried to throw him a curve ball by making him solve a problem she hadn't fully explained, he would give the right answer. He wasn't sure why she had it out for him. He was Professor Membrane's son, why was his skill in math such a bother to her? Did she just not like having a student that was better at math than her? Whatever. In a few more months he won't have to deal with her ever again.

Dib tuned the teacher out as she explained the steps he had gone through to the class, looking back at Zim. He saw that Zim was watching him now with an unreadable expression. Dib saw an odd purple discoloration to the tops of Zim's cheeks and lifted his brows, even cocking his head a bit as he silently asked the other what was up. Zim was pretty good at reading him by now. Zim's eyes narrowed and he flipped his hand dismissively, looking forward again. Dib looked forward too, curiosity spreading through him. What was that purple color? And Zim had seemed sweaty too, now that he thought about it. Was he sick? He wasn't sure he's seen Zim sick in the entire six years he's been here on Earth. Having allergic reactions and sometimes even throwing up in response to different foods and materials, yes. But an actual illness? He hasn't seen anything like that.

Zim had told him before that among its many other benefits, every irken's PAK was equipped with its own personal fleet of clever nanobots that complimented its owner's white blood cells, dutifully scouring the irken's entire bloodstream without pause, searching for harmful pathogens and destroying them with extreme prejudice. Their databanks were updated with every PAK update, keeping them always vigilant in finding new strains of disease and killing them before the irken themselves could be harmed.

It sounded impressive but Dib had to wonder how efficient Zim's nanobots really were. There was that whole bologna DNA thing when they were younger... Zim's PAK hadn't really seemed to do a thing to stop that, in fact Zim's reaction to it was even faster than Dib's. They were lucky that they just wound up recovering naturally after a few awful, smelly days. Still, Dib didn't dare bring up that Zim's PAK may not be working right. Zim tended to get... _moody_ at any implication that he or his PAK were flawed. Dib's learned that the hard way.

But he couldn't help but think that was what was going on now. Zim could actually be sick with something and his PAK wasn't fighting it off properly. It would explain the tension and the strange shaking, along with that flushed look to his face. Come to think of it, Zim's blood was a rather pretty pink color. Was that how it made Zim's skin look when he blushed? Rather than the red of a human blush, it was purple? Interesting, he would have thought he'd look more pink, though he supposed it was a lighter, more lavender sort of purple... sorta pretty, actually...

Zim's eyes snapped back over to him again, this time mouthing a silent but demanding, 'What?!'

Dib just shrugged. Yeah, Zim was definitely sweaty. And his eyes seemed to have an unfocused look to them, though who could really tell what Zim's actual eyes were doing beneath those contacts. He made a decision to ask Zim what was going on after class. He was pretty good at weaseling information out of him by now.

The rest of first period passed without too much of note. Dib copied down the math problems in the textbook that were due on Monday and got up as soon as the bell rang, the teacher giving an annoyed huff, but really, shouldn't she know by now when the class ended and make sure she was done talking by then? At least she didn't try to insist they stay past the end of the period.

Dib pulled his backpack on and turned to talk to Zim, only to see that the other was already gone. He hurried after him, accidentally pushing a few people aside as he raced for the door, muttering apologies that were accepted with resigned sighs. Pretty much everyone in the senior class was used to this. They've been dealing with it since fifth grade.

By the time Dib made it out into the hallway, Zim had disappeared into the crowd of students. When he first arrived, he had stood out like a sore thumb with his green skin and magenta uniform among the kids who were around the same height as him. But now almost everyone Dib knew has grown to be taller than Zim while Zim himself has only gained a few inches, so it was easy for the irken to just slip into a crowd and vanish.

Dib stood up on the tips of his toes as he tried to look over everyone. It helped that he was one of the tallest students, exactly as tall as his dad now, but he couldn't find Zim. He knew he had a woodworking class next. He had chosen it as an easy elective, though admitted he liked work that he could do with his hands, and in fact Dib has seen quite a few of his creations in the base. Zim was surprisingly skilled at the hobby and had even seemed flattered when Dib complimented him on his work once, though had immediately acted aloof and waved his hand as if it didn't really matter, claiming that a “limbless smeet” could make any of that stuff.

It made Dib a little sad how quick Zim was to dismiss his obvious skill in non-militaristic hobbies. He's seen Zim draw, cook, and build wonderfully on many occasions, he was incredibly artistic and creative, but anything that didn't directly contribute to conquering a planet and serving his empire was seen as frivolous and stupid by him. Dib wished he could help Zim value his talents more.

He shook his head upon failing to find his enemy and just took out his phone, writing a text as he walked the other way toward the chemistry classroom. Zim had gotten an Earth cell phone a few years back, as it was what all the kids were doing and he wanted to look normal. He didn't really text with it but Dib did see him playing games on it occasionally, and Zim also appreciated it for allowing him to quickly look up whatever incomprehensible thing the humans around him were talking about so he could understand and follow along.

 _You seem distracted, Space Boy. Something going on? GIR get taco sauce in your keyboard again?_ He didn't want to seem too nosy. Though Zim has so far failed to conquer Earth or even incapacitate Dib himself, he was still devoted to his mission and didn't like Dib asking about his plans. Even though he usually ended up just spilling all the details anyway. Idiot loved to hear himself talk.

He didn't get an answer until he was sitting at his table in Chemistry. He was talking to Zita, who shared the same table with him, when he saw his phone screen light up with a notification. He swiped to open the message and read it. As usual, Zim had written with the caps lock on.

_ZIM IS FINE._

Dib snorted. It took Zim that long just to write that? He texted back, _You sure? I saw your face looking purple and you were sweaty. Having another allergic reaction to something? Lol_

_ALL OF MY BODILY FUNCTIONS ARE WITHIN NORMAL PARAMETERS. MIND YOUR BUSINESS YOU UNDERDEVELOPED LARVA._

“Well he's in a mood,” Zita commented, having glanced at Dib's screen and immediately gathered who it was even without reading the full message. There was only one person in the school who texted liked that.

“Yeah, I don't know what's going on, he's being weird today,” Dib said. “I mean, even more weird. Did you see that weird purple color on his face during math?”

“No, Dib,” she replied patiently. “I think you're the only one around here who is constantly checking him out.”

Dib blushed at her wording. “H-hey, he may have chilled out a lot since getting here but he's still a threat to Earth and I have to keep my eye on him, if I let my guard down he could easily, I don't know... nuke the White House or poison all our groundwater or release a plague of genetically modified super mosquitoes...”

She just laughed. “You two crack me up with all your stories.”

“Oh come on, you've been there for so many of his plans! Remember when he hypnotized a bunch of us with Pustulio? And then the zit burst and flooded the classroom? It took us ages to clean that up! And what about the field trip that went nowhere because he was trying to fly all of us into a wormhole and I saved us and got the bus turned around so it came back to school! Or!” Dib gestured wildly toward the sky. “Or when he literally dropped a giant water balloon on the entire city! Come on!”

She smiled politely at him but he could see in her eyes that she had already rationalized all that stuff away as completely mundane disasters long ago. “Sure, Dib.”

Dib sighed and looked back at his phone, considering if he wanted to send another text in the last minute before class was due to start. “Well, whatever. I think something's going on with Zim and I have to make sure he's not planning anything.” He knew Zim would hate what he was about to type, but still sent, _If you want to talk, I'm here._ Then he double-checked that the ringer was off and pocketed the phone, looking up as the teacher finished marking down everyone who was present and then went to close the classroom door before starting his class.


	2. In Which Dib Seeks Answers

Dib wasn't surprised to see that Zim never answered him after that last text. Though Dib has had a few rather deep and emotional conversations with him, Zim always pretended they never happened afterward and would continue behaving like they were no more than sworn enemies. Like they didn't have a lot in common, that they understood each other on a level no one else in their lives ever have, that they had the potential to make such a meaningful connection if they just let themselves...

He groaned and rested his head in his hand for a bit. He was so tired of being Zim's rival. He was sure that if he just stopped fighting him altogether, Zim still wouldn't get anything accomplished. In fact, he has stopped before, whether to try working with his dad for a while or because he was too depressed or even just because he needed a break... yet Earth was fine. Zim would stop too. He would make up all kinds of excuses but Dib knew he saw this as pointless if he didn't have someone to witness his genius. He needed to be validated. And Dib was the only one here who gave him the attention he craved.

So really, Dib was only still confronting Zim because it was routine for them. It was comfortable. It made Zim so happy to have to fight for the planet's fate and for some reason, Dib liked seeing that. He wasn't sure why. With their history he should hate Zim's guts, but he didn't. He's grown fond of him over the years. And seeing the way Zim lit up at the sight of him, how his stance grew proud and he prepared himself for a confrontation, it made him feel strong. Zim respected him as a foe. Zim recognized him as a smart, capable, worthy adversary. And that felt good.

If they weren't enemies, they could be good friends. But Zim was too proud to give up. Even Dib has seen the signs that the Tallest sent him here to get rid of him and he thought Zim himself had realized it a few years ago. Yet he kept on with his supposed mission. He was obsessed with it. He needed to win the approval of his leaders. No matter how long it took.

Dib didn't get any more texts from Zim and he didn't get to actually see him until lunch. He headed to the cafeteria at a quick pace and got a small meal, but he wasn't very hungry. All he could think about right now was Zim. Theorizing on what was going on with him. Planning how he would deal with various scenarios.

He had just barely sat down at a table facing the door when Zim walked in too. Dib immediately noticed he looked worse than earlier. His chest was moving rapidly suggesting that he was breathing fast, that lavender color had spread further across his face and along the sides of his neck, and his skin actually shone with a thin sheen of sweat. Then there were the bags under his eyes and the shaky way he walked through the room, bumping into a couple people and hardly acknowledging them when they shoved him away...

“Zim!” Dib called.

Zim looked up and focused on him, perking for a moment. There was none of the usual contempt Dib saw on his face when he addressed him. He looked calm despite his tired behavior. He headed toward Dib's table and one of the other seniors he passed wrinkled her nose and said, “Ugh, Zim, are you wearing perfume?”

“Wha?” The calm expression disappeared and just like that, Zim had his usual annoyed scowl again, turning to look at the other. “Are you talking to me?”

“You see any other Zims around?” The girl, Jessica, gave him a haughty look. She eyed him up and down and then leaned a bit closer to sniff, then covered her nose. “You are wearing perfume!”

“No I'm not! Why would I soil my perfect natural odor by spraying those foul liquids upon myself?”

Dib snorted. He wasn't sure Zim even had an odor, he usually just smelled like whatever chemicals he's been working with or whatever GIR has spilled on him. But maybe irkens did have a natural scent and humans just couldn't smell it.

“I don't know but you're definitely smelly, how can you not notice?” Jessica asked. “It's like... it's like someone rolled a bouquet of roses through battery acid.”

“Tch. Your olfactory nerves are deceiving you.” Zim suddenly looked nervous, though. He hastily jogged away from her and got to Dib's table, sinking down across from him.

“Hey, how are- ohh yech!” Dib got a whiff of a flowery scent that almost would have been pleasant if not for the acrid sour sting that came with it. He jerked back to try and get away from it. “You didn't smell like that earlier!”

“I have no clue what any of you are talking about,” Zim said coldly.

“I think you do. Come on man, be honest with me. What's going on? Have you been working on some new experiment? Whatever it is, it's making you look like a fucking dumpster fire.”

Zim snorted but Dib could see him trying not to crack a smile at the phrase. “That's none of your concern,” he replied, his tone considerably lighter now.

“If it's something that'll threaten Earth, it is my concern,” Dib replied.

“It's not.”

Dib tilted his head. Zim wasn't usually so forthcoming. “And you expect me to just believe that? You've always got some scheme to conquer the planet, subjugate the humans, you know, the whole Invader thing.”

“Yes. But at the moment, I'm between projects. You have nothing to worry about.” Zim sighed, resting his head in his palm as he began staring off into space again. Every so often his shoulders trembled, and then he got out his fidget cube to begin clicking again.

“Something has you worried, though,” Dib said. “You've been acting weird all day. You never answered me about the blushing. Or the sweating. You look like you just came from a serious workout.” With Zim this close, he could also hear his breathing. It was faster than usual.

Zim shook his head. “It's personal.”

“If you're sick you should go home so you don't infect-”

“I'm not sick!” Zim screamed. The clicking stopped and everyone turned to stare at them.

Dib was too used to this to feel embarrassed. “Okay, fine, I'm sor-”

“How dare you even insinuate that I, with my superior immune system, could be sick! I am not sick!” He grabbed Dib's shirt and leaned in close so he could growl too quietly for anyone else to hear, “Becoming ill is for lesser species. Irken Elites do not get sick. To do so is a sure sign of having a defective PAK and I. Am not. Defective.” He roughly shoved Dib back.

Dib's eyes were watering from how strong the other's scent was up close. “O-okay, sorry, you don't have to be so dramatic.”

Zim grunted and began clicking the cube again, fast and rough. “What I am dealing with is something... is something normal, it's no cause for concern.” He sounded like he was trying to convince himself more than Dib.

Dib sighed, wishing Zim would just be honest with him. “Well, are you gonna go get lunch, at least? You look like you could use the energy.”

“Hmph. I don't feel like being close to other people right now, and that line...” Zim looked toward the lines of students still waiting for food. “Is full of people. Ugh.”

Dib knew Zim wasn't exactly social but for him to be that opposed to being near any humans? He felt like that was significant, but of what, he had no clue. He looked down at his tray for a few moments as he took a few more bites, then his eyes landed on the chocolate pudding cup he had gotten. He had kinda been craving something sweet, but...

“Here.” He passed it over to Zim along with a spoon.

Zim's head snapped toward him and his eyes widened. “Oh? Are you... this isn't some trick, is it?”

“You can clearly see it's a sealed thing of pudding, I haven't touched it. You can have it.” Dib waited to see what he would do.

After a couple seconds of consideration, Zim gently picked up the container and spoon, looking at them before looking up at Dib, his expression suddenly relaxed again. Happy, even. “Thank you.”

Dib smiled awkwardly. “You're welcome.” He didn't get to have a lot of peaceful moments like this with Zim. He liked it. There was a comfortable feeling between them as Zim peeled the lid from the pudding and gave it a sniff before humming and digging in. He loved chocolate. Claimed it was one of the few good things about Earth, along with the abundance of cheap sugar and the quality of the cartoons.

The longer Dib sat there with him, the more accustomed to his strange new scent he became. He still wondered what it meant but could tell Zim didn't want to explain, so he decided to just try asking again later. For now, he just sat there slowly inhaling it while he ate, theorizing what the smell was. It was definitely something being released by Zim himself. Zim was rather insect-like... could these be pheromones? If he was an irken, would that scent mean something to him?

It really was a unique smell... it was making the inside of his nose tingle. It reminded him of biting into something tart yet sweet, like a fruit that was just acidic enough to burn but not enough to truly hurt, just to provide an interesting sensation. He found himself licking at the roof of his mouth as though trying to clear a taste from it. His lips parted a bit as he breathed through his mouth instead for a few moments. Even like this, that scent tingled. The sensation was starting to spread down his throat.

He abruptly closed his mouth and grabbed his carton of milk, gulping it down. Zim watched him curiously but didn't say anything, still working on the pudding. Dib wondered if Zim knew what effect his scent was having. Zim didn't seem concerned. Maybe it was nothing. Or maybe, as a human, Dib could be experiencing a negative reaction to it...

He reached up to wipe at his forehead, starting to feel hot. “Oh God, I think the air conditioning went out again.”

“Hm?” Zim pulled the spoon from his mouth. Dib's eyes followed the string of saliva that went with it.

“The air conditioning,” Dib repeated, tearing his gaze away. Why the fuck had that caught his attention? “You know how it broke just before summer break last year and we were all miserable because apparently the county didn't have the budget to fix it?”

“Ohh yeah.” Zim scowled as he remembered. “Awful place. I finally went up there to fix the damn thing myself. Any monkey with a wrench could have done the same.”

“Yeah. Well I think it went out again, because it feels hot in here.” Dib lifted the front of his shirt to mop at his face with it. He heard a clatter and lowered the shirt to see that Zim had dropped the spoon and was staring with wide eyes at his torso. “Zim?”

“What?” Zim jerked his head up, his entire body stock still. “I didn't do anything, I'm normal!”

Dib gave him a suspicious look. “Yeah. So. Is it hot in here to you?”

“Hot, well, uh...” The flush on Zim's face darkened. Fresh sweat beaded at his temples and he grabbed a napkin from the nearby dispenser to clean his face off with. “A-a little, yes...”

“So it's not just me.”

“No. Not just you.”

Dib looked around at the other students. No one was paying attention to them, carrying on their conversations and eating, but none of them seemed bothered by the temperature. They all looked comfortable. Dib frowned and returned his gaze to Zim, who had gathered up the empty pudding cup and dropped it onto Dib's tray along with the spoon.

Placing his hands on the table, Zim unsteadily got up. “I think I'm just going to head to my next class.”

“Wait.” Dib moved to lean across the table, covering Zim's hands and looking into his eyes. “I want to ask again. Is there something going on?”

Zim's arms trembled and Dib saw his eyes flick down and up a few times, like Zim was torn between looking at his face and looking elsewhere. Zim briefly nibbled his lower lip and then nervously flicked his tongue against it before saying, “No. Nothing.”

“You can talk to me, you know.”

The pupils of Zim's contacts seemed to expand slightly. Then Zim huffed and narrowed his eyes, pulling away. For some reason, Dib's chest ached at the sight of him retreating. “I can't,” he said stiffly. “Not about this.” Then he did a clumsy about face and marched out of the cafeteria. He was running the moment he got out the door.

Dib slumped a bit in his seat, heart racing. His mouth was dry and that heat was fading as quickly as it had come on. He stared down at the table as he tried to figure this out. “What the hell?” he whispered softly. One of his hands drifted to rest in his lap without him thinking about it and he gave a little jolt at what he felt. No, he wasn't- he moved his legs and lightly cupped his crotch to make sure. He was. He slammed his hand onto the table. “Oh what the hell!” he repeated louder, to hardly a glance from anyone else, though a couple teachers who were supervising the cafeteria shot glares his way. He waved in apology and then gripped his forehead as he stared into space. Okay, he definitely needed to get to the bottom of this.


	3. In Which Zim Explains

The only class Dib shared with Zim after lunch was the last period of the day, chorus. Dib's only elective this year and one that he quite enjoyed. He wasn't the best singer but he liked singing anyway and there was very little actual work to be done beyond the teacher giving them a few exercises in identifying key signatures and teaching them to read music. Other than that, classes mostly just consisted of learning to sing various songs in three part harmony. Most of his classmates here were girls but there was still a strong tenor section of about a dozen boys. And he always stood right next to Zim, using the irken's surprisingly pitch perfect voice to keep himself in tune.

So he immediately noticed Zim's absence when he took his seat. He looked around to see if he was mingling with the other students who were chatting before the bell rang. He wasn't. So he looked at the door, expecting Zim to sweep in with seconds to spare.

The bell rang and everyone made their way to their seats. Still no Zim. Dib sighed. Must have just gone home. He turned his attention to their teacher as she went to sit at her piano, which the three singing sections were arranged in a semi circle around.

“Okay, quiet down now, we have a lot to rehearse today, our concert's in two months!” she said.

It was going to be Dib's first time participating in one of the end of the year concerts that the band, chorus, and other musical classes put on. He was kinda looking forward to it and had even invited his dad, though he doubted he would make it out for it. He had apparently barely managed to schedule time for Dib's high school graduation in a few months. Luckily, Gaz would be there at the concert. Mostly because she was part of the hand bells group, but she promised she would clap for him.

The class was soon being directed to stand to open up their lungs further as they went through their warm ups, singing up and down various scales along to the piano, and Dib quickly missed hearing Zim's loud but clear voice right next to him. He hoped that whatever was going on, the other was okay.

Chorus went well, though Dib got called out a few times for being out of tune. Each time he apologized and made himself listen more closely to the others so he could follow along, but his mind just wasn't on the singing today. He was incredibly relieved when the class was finally over and school was done for the day. He pulled his backpack on and headed out into the hall, texting Zim. _Missed you in chorus, it was surprisingly hard to carry a tune without you screaming it next to my ear._

He really wasn't expecting an answer and held his phone at his side as he headed to his locker, going through it and double checking that he had all his homework for the night and any required textbooks. Once satisfied, he put his backpack on again and closed the locker, going over to Gaz's to wait for her.

He was waiting there for a while before realizing today was Friday and she would have gone right over to her gaming club right after her last class. He was her ride home from school today so he would have to wait for her. And delay going to check on Zim.

Dib sighed and made his way toward the computer lab. He supposed he could at least hang out in one of the meetings while waiting. He glanced through windows of various rooms before finding the one the club was held in, going inside. Gaming club was pretty much just a thinly veiled excuse to use the school computers to competitively game against each other, though every year it did hold a canned food drive to keep the school administration appeased. There were also a few consoles installed in here, which is where he found Gaz, fighting another student on Fatal Combat. She was winning by a wide margin.

“Hey, just waiting for Gaz,” Dib said to the teacher in charge. Mr. Harrison, who was the school's computer science instructor, nodded. Dib was one of his favorite students and he was familiar with him waiting on Gaz in the meetings.

“That's fine, plenty of free seats, oh and we started a Digcreate server if you want to join, it's on the latest release version and the address is on the board,” Mr. Harrison said brightly.

“Eh, I'll think about it.” Dib liked a good single-player game of Digcreate or even one with just Gaz, but he didn't trust the other students that much. Especially some of the freshmen in here that were definitely in full blown Internet troll mode.

“Join our server, loser!” Gaz yelled back at him. “You're good at bluestone and we wanna have an automated mob farm.”

“Ah just build one of those fall traps, works just as well.”

“Those are slow, I'm talking something big and industrial that'll turn out hundreds of drops an hour.”

Dib sighed and rubbed the bridge of his nose, glancing over at someone who seemed to currently be playing on said Digcreate server. They were currently hacking away at a tree with a pickaxe and something about that made him very uncomfortable. “Yeah uh. I'll consider jumping on to help you with that but I don't think I wanna run around on a server with the rest of these guys.”

The other club members booed at him, but it was all in good fun.

He took his phone out to turn its volume back up and noticed that he had a text from Zim. He quickly opened it.

_Something came up. Had to leave for day. I'll be back on Monday. Probably._

He stared at the message for a bit. If not for the name at the top of the screen he wouldn't even recognize this as from Zim. It was bizarre seeing him send something without it all being capitalized. He really must not be feeling good. _Probably?_ he typed. _Are you sure you're fine?_ He sent it and waited. The reply only took a couple seconds.

_OF COURSE._

There it was. Dib considered what he wanted to say next. Zim's mood has been wildly unpredictable today, swinging between polite and furious at the minor provocation, and he didn't want to set him off. Then again, it wasn't like he could really do much to him over the phone. He texted, _Again, if you want to talk about anything, I'm here. You can trust me._ He had given up on trying to turn Zim in ages ago. Zim could vent to him about whatever crazy alien things were happening in his life and Dib would just listen, which was very satisfying to Zim's ego. Once Zim realized that Dib really was keeping the information to himself, he became more honest with him, but there were some things he still kept private. Mostly emotional matters, Dib has noticed. Zim had no problem ranting about all the things and people who have slighted him. The moment Dib asked him about any feelings aside from anger, Zim changed subject.

So if Zim was hurting right now, Dib doubted he would admit to it. He didn't like showing weakness. Even if Dib told him that it wasn't anything to be ashamed of, no one could be strong all the time, and it was okay to feel sad or vulnerable or confused... Zim just laughed or yelled over him. Those feelings weren't for irkens, he'd insist. Only babies and defects are weak and emotional.

It just made Dib feel bad for him. He was so emotionally repressed and he refused to see anything wrong with it. He was brainwashed by his society and Dib wasn't sure he'd ever be able to break through that. But he felt like he had made some sort of connection with Zim today. Sitting at the lunch table, Dib giving him the pudding... there had been something beyond anger and resentment in Zim's eyes. Zim had been happy. He wanted to see that side of him more.

The phone dinged. _I just need to be alone._

_You sure?_ Dib asked. _I can be right over as soon as Gaz is done with her club, seriously, you've been acting weird and I wanna make sure you're not planning something dangerous._

_I ALREADY TOLD YOU I'M NOT._

_Why would I just believe you? You're an Invader, it's what you do!_

_YES BUT I'M NOT WORKING ON ANYTHING RIGHT NOW._

Dib believed him. But he liked riling him up too. _Maybe I'll just break in and see for myself then._

_DO NOT._

_If you really aren't working on anything, you have nothing to hide. So do you want to tell me what's really going on?_

There wasn't an answer for a while and he was sure Zim had just left the phone and gone to do something else. Or maybe he was coming back to the school just to kick his ass. Wouldn't be the first time Dib's provoked him that far.

Then, after he had spent a few minutes watching Gaz play her game, he finally got a text.

Zim had gone back to not using caps. _If you come over, I will explain. I must tell someone and GIR is too childish to understand._

This was new. Dib's mind raced at the possibilities. Though he focused on one in particular. GIR is too childish. Zim has been sweaty and flushed. That scent, the heat, Dib's reaction to Zim getting close to him...

He was pretty sure he knew what it all meant. He didn't want to make assumptions, Zim was an alien and this could end up being something entirely different, but he just had a gut feeling about what this was.

He was impatient throughout the rest of the meeting and as soon as Gaz was done, he was telling her he needed to take her home so he could go see Zim.

“Why?” she replied. “Late for a date?”

Dib blushed, voice wavering as he said, “N-no, of course not. Ew. He's just been really off today so I'm gonna go investigate.”

“Oh come on, leave him alone. Even if he is planning something, you know he's incompetent.”

Dib sighed. He did know that. “Yeah. But this is different. I don't think it's actually relating to a plan. I think he's actually got something wrong with him, physically. Have you seen him today? He's all shaky and nervous... he says irkens don't get sick but well, I'm pretty sure there's something wrong with his PAK and he just doesn't like talking about it.”

“If there is something wrong with him, don't expect him to tell you. He's too proud.” Gaz walked out of the room toward her locker.

“He usually is. But he said if I come over, he'll explain what's going on. He's never this open with me. I have to go see what it is.”

“Might be setting up for a trap,” she mused. “Maybe he's pretending to act sick so you'll let your guard down and he can finally kill you.”

“If he wanted to kill me he would have done it already. He needs to keep me around because I pay attention to him. Way more than the Tallest do.”

“Which is pretty sad. Idiot just needs to give up already and accept that he's stuck here. Maybe then he'll chill out some.” Gaz finished getting her stuff and put on her backpack. “Okay, fine, let's go home.”

Dib quickly drove her back to their house and handed her his backpack to take inside with her, then told her he'll be back in a couple hours probably. If not, don't worry about him, though if he's still not back by tomorrow, definitely text him.

“Whatever. Have fun.” She went inside.

Dib backed the car out and headed over to Zim's place. His hands were shaking a little on the wheel along the way. He was a little anxious but also excited. He had the feeling he was about to learn something very new about Zim and he was looking forward to it.

Once parked in front of Zim's house, he made sure the car was locked and then went to the door, raising a hand to knock, but it was opened before he even got there.

“Dib,” Zim said. He was out of disguise and his antennae were up, the ends twitching, and Dib swallowed at the thorough way Zim's eyes checked him out. “So you came.”

“Well yeah, I gotta know what's going on with you. You're really going to tell me?”

“Yes,” Zim sighed. He invited Dib in and closed the door, walking through the living room. He briefly looked at the couch, then shook his head and kept going, leading Dib to an elevator.

They were quiet as they took it down, but Zim kept shooting Dib glances, trembling occasionally. That sharp, sweet smell soon filled the air and Dib grew lightheaded. It seemed even stronger now. Was it being produced by Zim's antennae? His body grew warm and something in his gut twisted, making him think back to earlier in the cafeteria. Something about that smell and how Zim had looked at him... it turned him on.

He was getting turned on again just standing next to him. He was pretty convinced of his theory now, but he was going to wait for Zim to tell him.

The elevator reached its destination and Zim got out, gesturing for Dib to follow with a flick of the wrist. In the open space of the lab, the scent wasn't as overpowering, but it was still a constant presence. They walked over toward the main computer screen and Zim sank into the chair there, while also pulling over a second, less-comfortable looking one for Dib. “Sit.”

Dib sat, folding his hands awkwardly in his lap. This chair was a bit small. Maybe GIR used it?

Zim was silent for a while, just staring at him and apparently thinking about how he wanted to start. Then he said, “What we discuss will not leave this room.”

“Sure,” Dib agreed.

“I mean it. Do not tell GIR. Do not tell any of those wretched teenagers at school. This is very private and very shameful.”

“Okay.”

Zim rubbed at his face, groaning low in his throat and wiping sweat off with his sleeves, before looking somewhere off to the side of Dib's face and saying, “I am in heat.”

So that was it. It was all just... Dib broke into relieved laughter at the admission. Heat! He's been fretting about Zim's behavior all day because of that? Zim quickly started to look upset at the laughter and Dib forced himself to stop, saying, “Sorry, didn't mean to laugh, just... I really did think you were sick and just didn't want to tell me, or that this was some big trick to throw me off. But heat! So, like a mating season?”

“Yes.” Zim nodded. “It is an annual event. Annual for us. Our years are quite long and my last one happened before I came here. However, I...” He hesitated, chewing on his lip. Dib's eyes were strangely drawn to the sight just like they were earlier. Zim continued, “There is nothing wrong with me! Just wanted to put that out there! There's just biological variance between individuals and my heat has always been... strong.” He fiddled with the hem of his shirt. “Quite strong, uh. Very uncomfortable, in fact. Medics have said it reminds them of how heat was in the old days. You know, before we had PAKs to regulate our hormones and various bodily processes. Before cloning was the standard for producing young. Back then, it was a big event that pretty much kept every sexually mature irken from getting much done at all. They were driven by powerful, disgusting urges to mate. I suppose at the time it was good, it produced plenty of smeets. Kept us numerous. Strong. But now, we don't need to mate anymore. On the orders of the Control Brains, we're sterile. Yet heat persists in most of us. It's a deeply ingrained part of our biology, you see. Difficult to edit out with genetic modification. So it's mostly allowed to stay, given that we can resist its allure and continue our work anyway. And there's medicine for those, like me, who have stronger instincts.”

This was fascinating to Dib. He loved learning about Zim's people, even if much of their culture was disturbingly violent. It was nice to hear about something different. “So, you're like this even with the medicine? Man, I can't imagine how much it'd suck without it.”

Zim let out a weak laugh. “Heh. You don't understand. I don't have the medicine right now. I sent an order for it, but it hasn't arrived.” He grinned but it looked strained. “Sure, I requested it weeks ago. Irk always produces plenty yet they're claiming difficulty in getting a bottle out to me. It's... I'm sure they're working it out. Earth is far away and hard to ship to. I'm sure it'll be here. It's just late.”

Dib had a sinking feeling. “Oh. Well, uh...”

Zim kept going, “I even asked the Tallest if they could maybe speed things along for me and they seemed to think it was funny, but probably just, you know. Laughing about me not preparing sooner. They're very funny, my Tallest. Haha, I'm their best Invader, I'm sure they don't want me inconvenienced. They'll make sure that medicine gets to me.”

“Zim...”

“It's not like they'd want me to suffer! This is only the first day and the feelings are almost unbearable, any longer and... and I'm not sure what I'll do, and they must know how strong the urges are, surely they don't want me losing control. Imagine how humiliating that would be!” Zim's blush was bright and he was chuckling and resolutely not looking at Dib, checking out every other part of the room instead.

“Hey. Uh, I don't think that medicine is coming,” Dib said carefully.

Zim's eyes snapped back over to him, antennae laying back. “Why wouldn't it be?”

“Well, Red and Purple-”

“The Tallest.”

“...The Tallest may not actually be sending it. Maybe they... would think it's funny. For you to suffer.”

Zim gave him a long, silent glare. “They aren't that cruel.”

“Seriously? I've barely talked to them and I know how cruel they are. They regularly seem to hurt other irkens around them as a joke. Why would you be any different?”

“Those jokes were always, eh, played on inferior irkens. Very inferior. Far below my status. They would never do that to me.”

“How can you be so sure? Maybe they're bored. Maybe you're an easy target that won't complain.”

Zim fidgeted. Dib could tell he didn't like this line of questioning. “Look,” he snapped. “The Tallest love me. They will be sending what I requested, and once I have my medicine, I can feel mostly normal again. At least, the heat will be easier to ignore. No more of this dumb blushing and sweating. No more icky feelings in my body.”

“And what if days pass and that medicine doesn't show up?” Dib asked. “Will you admit they don't care if you're in pain, or will you just keep making excuses?”

Zim's tone turned icy. “If they aren't able to get me the medicine, I'm sure it will be for a very good reason. I trust my Tallest. Now, I told you what has been bothering me. You may leave.”

“What? I just got here.”

“So? Your question has been answered. Get out.”

Dib quickly cast for another question he could ask. “Wait, uh... is that smell part of heat?”

Zim sighed, lacing his fingers together. His antennae moved forward and flicked toward Dib, and the scent grew strong for a few seconds, making Dib's mouth and throat begin tingling once more. Blood rushed south and he was glad he was sitting down. “It is. They are pheromones. Other irkens can use them to determine qualities such as overall health along with checking that a potential partner is not related to them. Then, once a pair decides to court, the pheromones are used to communicate interest. They work to trigger sexual arousal too, I once heard.”

“Yeah, that last one definitely makes sense. Not to be too personal or anything, but well...” Dib crossed a leg over the other. “It made me hard earlier. You know, at lunch.”

“I see,” Zim replied.

When he didn't reply further, Dib added, “And right now. So can you make the smell stop or something?”

“I can't stop it. It's natural. All I can do is try to cover my antennae. Or waft the scent toward interested parties.” Zim gave him an analyzing look. “This is very interesting, that it affects humans. I may need to report this. No doubt there are xenobiologists back home who would love to hear about it.”

“I'm sure humans aren't the only species affected by pheromones literally designed for mating,” Dib replied.

“Actually, it's quite rare,” Zim said. “Irkens evolved to use these chemicals exclusively with other irkens. There's no reason these chemicals should cause the same reaction in completely different species from other planets. To most creatures the smell is apparently repugnant. It burns, they say. And I heard several humans complain about it today. But you. You're experiencing the natural response an irken would. It's very interesting. I've scanned you and examined your DNA closely, as your intelligence once made me suspect you could be part irken.”

“What?”

“You are 100% Earth monkey. Just a very clever one, with a few modifications made to increase your strength and whatnot, but otherwise a normal specimen of this planet. So why do my pheromones affect you?” Zim was looking at him very closely now. “Is it just that I wasn't in proximity to anyone else long enough? Or is your susceptibility... unique to you?”

Dib could admit, the scent could be a turn on just for how purely exotic it was, how it was such a powerful sign that the creature across from him was an alien, someone not of Earth, so strange yet interesting, and so very attractive.

Attractive?

Dib scooted his chair back a bit. “I don't know, I mean you're right, there's no reason your pheromones should give me a response, humans don't even really use pheromones ourselves... at least, I don't think we do, not consciously, though of course there are still certain scents that can arouse us, usually ones specific to someone that is already a sexual interest... like their partner's sweat, or just. Oh wow.” He gripped his forehead. “I'm actually attracted to you.”

“You should be, I'm amazing. Well! Isn't this interesting! I'm in heat and your body is responding to it. Hm.” Zim's tongue slid over his lips and Dib followed it, pants growing tight.

“Y-yeah, I am, it's pretty embarrassing actually... I think I've learned enough and should go.” Dib stood up and Zim did too, immediately crossing the distance between them and grabbing his collar.

“No!” he barked. Dib froze and Zim's expression softened, a smile crossing his face. “No. Stay.”

“You want me to stay now? Just a while ago you were telling me to get out.”

“I changed my mind, Dib-stink.” Zim let go of Dib's collar but didn't step back, instead running his hands down Dib's front. “I think I would like to experiment with this.”

“Experiment? I'm no guinea pig.”

“Don't act like you aren't curious too.” Zim's eyes glinted at him. They looked hungry. Desperate. “Let's call a truce and study each other. I know you want to.”

Dib wanted that badly. He was also aware that this was taking a very strange turn and it might lead to things he'll regret. But the way Zim smelled and how he was looking at him was starting to drive him crazy. It felt like he's wanted to do this for so long. He took Zim's hands and squeezed them. “You sure? I don't know much about what's happening to you or what it really means in your culture...”

“It's fine. All that matters is that I want this.” Zim's eyes were dark. Hooded. They promised delightful things. Naughty things. Dib's pulse was pounding in his ears. This was going so fast. Why did it all feel so right?

Feeling like he was in a daze, he allowed Zim to turn him and back him up, pushing him firmly into the chair Zim had sat in.


	4. In Which Dib Learns Some Irken Biology

Dib sank down into Zim's chair, finding it quite comfortable, and Zim's hands moved down to his stomach, pressing up under his shirt as he sank onto his lap.

Dib's breath caught. “You sure you want this?” he asked breathlessly. “M-maybe this season, the heat... is messing with your brain. Making you act... like you usually wouldn't.”

Zim clicked his tongue, hands exploring further up and settling on Dib's chest. “I'm still myself. Heat just makes me want to mate. I've been suffering all day trying to resist... if I can relieve that pain with you, well. I'm going to.” He swiped a thumb curiously against one of Dib's nipples.

Wound up as he was already, Dib moaned and arched at the touch. He felt way too sensitive, his erection hurting as it strained inside his pants, all his clothes seeming too tight, too hot...

Zim smirked and raised his antennae, fascinated by that reaction. He pressed again against the nub, slowly teasing it, and felt the other shiver under him. The human's need pressed deliciously between his legs and he gave a small grind down against it.

Dib's hands went to his waist. “Nngh, Zim...”

“That's it,” Zim murmured. He rocked his hips gently forward and back and felt the other move to follow. “Enjoy it.”

Dib panted, finding it hard to think straight as arousal overtook him. He was hardly even noticing the sharpness to Zim's pheromones now, mostly just enjoying their flowery sweet scent, how they made everything around him grow foggy while his nerves seemed to grow ever more sensitive, his body becoming more reactive to even the smallest touches. Part of him wanted to hold on, to keep himself focused and even resist what was happening. The rest wanted to give in. Give in and take whatever Zim did to him.

He closed his eyes when Zim leaned in to put their faces together, lips parting, but the other didn't kiss him like he expected. Instead, he pressed their foreheads together and seemed to try and nuzzle between his eyes, but Dib's glasses got in the way.

“Tch.” Zim pulled a hand out of Dib's shirt and took his glasses off, placing them aside on the computer console behind him. Then he pressed their faces together again, finally managing to nuzzle him how he wanted.

It was surprisingly intimate. Dib opened his eyes a crack and watched him, nuzzling back. Their lips brushed and Dib wondered if this was how irkens kissed. He could feel Zim's antennae in his hair too, the tips stroking through the strands before finally seeming to wrap around his cowlick.

Well, if Zim was interested in exploring him... maybe he won't mind if Dib explores him right back. There was a lot he was curious about. He moved his hands from Zim's waist around to his butt, squeezing it. He felt the other smile.

“That's it, touch me,” he purred, hips moving a little harder. Dib felt up under Zim's top, lightly digging his nails into his back, and Zim arched with a pleased moan. Dib was surprised at how deep and throaty the sound was. And yet, when Dib went even higher and gently felt under the wires where Zim's PAK attached, he heard a much softer moan, almost a whimper.

“Is this okay?” Dib asked as he rubbed. “Can I touch you here?”

“Yes, just don't pull too hard on the wires themselves. Ohh, that feels good, I can never reach that spot myself...” Zim pressed their fronts together, both hands going to Dib's waist, fingers using his belt loops for support as he thrust against him.

“A-ah, fuck...” Dib squeezed his eyes shut, body shuddering. It felt like he was so close already. Just from grinding through their clothes! But he didn't want to finish inside his pants. So he quickly moved Zim's hips back away from him, and when the other immediately complained, he distracted him by kissing him.

Zim jumped but didn't pull away, instead waiting to see what Dib was doing before carefully responding. Dib could feel his hesitation but that was fine, he didn't really know what he was doing either. He began blushing hard as he really took in how it felt to have Zim's lips against his, softer than he expected, not really plump like human lips but still nice.

They separated after a few moments and Zim gazed at him, brushing a couple fingers over his mouth. “Well,” he commented. “I think I get why humans do that now.”

“Yeah, it's pretty nice, huh?” Dib asked.

Zim nodded. “Mhm. Do it again.”

Dib wrapped an arm around Zim's middle and kissed him again, and Zim cradled his cheeks as he kissed back, tilting his head a bit. Dib dropped his free hand to his lap, quickly opening his fly to try and relieve some pressure. He lifted up from the chair slightly so he could work his pants down from his hips, along with his briefs, just enough to try and let himself out.

Zim hardly noticed the shuffling, caught up in how Dib's mouth felt against his, experimentally running his tongue along Dib's lips and purring with delight at how the other moaned and opened up for him. Next thing Dib knew, the kiss was turning deep and Zim was making out with him, pushing him firmly back against the chair in his eagerness.

It was hard to breathe but Dib didn't care, guiding Zim back down onto his lap and continuing to grind with him, gasping now at how good it felt feeling fabric against his bare skin. Zim felt quite hard now and Dib could feel a dampness to his crotch. It only excited him more. The other was so wet and Dib wanted him to get his pants off so he could explore him further.

“Ohh, Dib...” Zim drew back, his tongue teasing along the roof of Dib's mouth before fully retreating, and Dib's head was spinning as he opened his eyes to look at the other. “You need this bad.”

“Not as bad as you need it,” Dib retorted, feeling between Zim's legs with a hand. Touching him like this, he was able to better explore the shape of his arousal and what he found was very intriguing. Especially toward what seemed to be the base, where that slickness was pooling, soaking through Zim's pants.

Zim chirped softly and grabbed Dib's wrist, pushing it back. He was smiling though, antennae still in Dib's hair, trembling with anticipation. He looked down and seemed to examine Dib's cock for a moment, then he said, “Well, you've already exposed yourself to me... suppose I should do the same.”

“Yeah, if you want,” Dib said casually, trying to mask just how eager he was to see how Zim looked. To his surprise, Zim actually stood up, though Dib understood when he backed up and began undressing. Fully.

Dib stared as more and more of the other's skin was revealed, letting him see toned muscles and the ridges of bones jutting up in strange places, similar to a human but just different enough in placement to reinforce how alien Zim truly was. When Zim's gloves were off Dib noted that he had sharp claws instead of fingernails. Dib's gaze traveled across his chest and stomach, and though it was a little hard to see without his glasses, Zim was close enough for him to tell that he had no nipples or belly button. Made sense, he wasn't a mammal and he was born from a tube, he would have had no need for an umbilical cord. But it was still strange just seeing smooth flesh where he expected those features to be.

Zim slid his boots off and Dib noted that his three toes also had claws, though they seemed to be filed down and kept more blunt, likely so they wouldn't stick to the insides of the boots.

Then Zim was at last slipping his waistband down and Dib leaned forward slightly, but Zim smirked and turned to put his back to Dib, teasing him. Dib gave an indignant, “Hey,” but really he didn't mind, checking out the curve of Zim's back and his quite shapely ass instead.

Only once Zim had completely stepped out of his pants did he turn back around to face Dib, posing. “So, what do you think? Flawless, am I not?”

“Oh yeah,” Dib said, licking his lips as he looked him over, taking in all that soft green skin that was now available to him, though he was soon focusing on what was between his legs. He was greeted with the sight of a long, plump, reddish tentacle that held itself up, the tip moving serenely back and forth, a small amount of what he figured was precum or maybe lubricant rolling down from it. Zim stepped closer and Dib could see that the tentacle was segmented, explaining how it was able to flex the way it did.

He reached forward and the other's cock actually moved to meet him, the tip slipping between his fingers and spreading that liquid along him. It was slick and warm.

“Whoa, this is so cool,” Dib commented, feeling a little silly as he said it, but Zim just hummed in satisfaction.

“Of course I am. My body is far superior to yours.”

“Okay, so your dick is a really flexible tentacle thing, but mine does its job just fine too you know.”

“Yes, yes, I'm sure your plain anatomy certainly tries its best.”

Dib rolled his eyes and pulled Zim onto his lap, pressing his cock up against the underside of Zim's, and the other shivered with pleasure. “Would you like a demonstration?”

Zim met his eyes, grinning at the challenge. His cock wound itself slightly around Dib's and moved up and down. “Certainly. Impress me, human.”

Dib gripped Zim's waist and Zim held onto his shoulders, Dib leading their pace as they rocked themselves together again. It was much more intense now that it was skin on skin, and both were incredibly turned on by the alien feel of the other. To Dib, Zim's skin seemed firm and scaly, but it had just enough give to it that the grind was thrilling. Especially with how the other could wrap around him and squeeze from all sides. To Zim, Dib's skin was soft and hot, his length quite rigid compared to how an irken's would be able to wrap back around him, but he liked this. It still felt amazing having it rubbing along him. He kissed Dib as he moved with him, both fumbling to find a good rhythm that worked for them, but this was still getting to them. This was exactly what Zim's been needing, it was so satisfying, just having the other close, inhaling his musky scent, feeling those tremors in his tall body, the way he just gave in to Zim's every desire...

Zim decided he needed more than this. His insides were aching for touch as well and while Dib wasn't irken, he was sure his organ would work just fine. He pulled his lips away and waited for Dib to open his eyes and look back at him. He liked how large the other's pupils had grown and how red had spread across the other's face, revealing how worked up he has gotten. It was nice to see someone besides himself in such a state.

Zim considered how he wanted to suggest they go all the way before deciding to just be blunt about it. “I want you inside me,” he murmured.

Dib's eyes widened and Zim felt his hips twitch. “O-oh? I mean, yeah, we can... if you want to, that's-”

“Stop stammering, it makes you even more pathetic.” Zim pulled his length away from Dib's and lifted himself higher over the other, reaching between his legs and ease a finger inside himself, making sure he was ready. He had grown quite relaxed already, lubricant dripping out of him, and he dreaded the mess he was going to have to clean up later. Luckily, most of it seemed to be getting on Dib's legs.

“Obviously you don't think I'm that pathetic, since you're still having sex with me,” Dib pointed out.

“Yes, well, don't let it go to your head.” Zim slipped a second finger inside, stretching himself a bit; judging from the size of Dib's tip, he was going to need a little more preparation.

Dib looked down to watch Zim finger himself. “Oh wow. That's hot.” He was so ready for more, he's never gotten this far with anyone and though he had never been that worried about it, he was still greatly looking forward to this. It was all too fitting that his first time having sex was with an alien.

“Mm, you ready for me?” Zim asked, pulling his fingers away.

“Oh yeah, so ready,” Dib replied. He idly thought that maybe he should have taken advantage of Zim undressing to get his clothes off too, but whatever... he just pulled his arms out of his coat and let it fall from his shoulders, and pushed his pants and underwear just a bit further down to make sure they were out of the way, but he was too horny to bother doing much more.

Zim pressed down onto him and Dib felt that he had plump, slick lips just under the base of his cock. He exhaled and held onto Zim's waist, positioning him a little better and then helping him ease down. It was a strain on Zim's part but once he got Dib's head inside, the rest was smooth.

“Aah, so big...” Zim moaned as he gave himself a few pumps up and down the first inch or so of Dib's cock, acclimating to it.

“Don't hurt yourself,” Dib teased.

“I can handle it,” Zim assured him. His fingers fumbled a bit as he searched Dib's front for somewhere to grab, before just settling on holding his arms as he pressed his hips down. Dib moaned and pressed back up to meet him, Zim was so tight and hot inside, and while he wanted Zim to take this at his own pace, he wanted so badly to just bury all the way in him and get it over with. He wanted to be completely surrounded by the other's body, his insides were ridged and squeezed so wonderfully around him, muscles seeming to flex and draw him in deeper, deeper...

Dib leaned his head back and gasped for breath as his own muscles tensed, feeling the familiar coil of tension inside him, ohh this was getting him so close and they were barely getting started...

Zim was panting already but he was still going, occasionally lifting to give himself a break and then going right back down, hips jerking each time he got Dib in further, and Dib looked down at him through half-lidded eyes, watching his lithe body move, sure that he could see the other's belly actually begin to bulge out around him... it was so hot he could barely take it.

He kept one hand on Zim's waist and moved the other to one of his thighs, going under it and then lifting it to spread him further open, giving a couple harder thrusts that let him go in almost all the way.

“Dib!” Zim cried out and then abruptly bit into Dib's neck as the feelings of pleasure and pain briefly overwhelmed him.

“Ah!” The bite hurt yet something about it felt good to Dib too, the stabbing pain a thrilling addition to his pleasure, and without even realizing it was about to happen, he found himself abruptly finishing.

The orgasm was so sudden and intense it knocked the breath out of him, making him cling to Zim and keep him firmly seated on his cock as he filled him up.

Zim let out a strange noise, something between a yelp and a chirp, and Dib felt his antennae yank away from his hair and the other's claws dig sharply into his arms. Dib recovered in time to see Zim lifting up on his knees and pulling roughly off of his length, groaning as he lifted a leg and looked at the mess dripping out of him. He lifted his gaze to Dib's and looked outraged. “Did you really just release your disgusting mating fluid into me?”

Dib was in a daze but Zim's accusing tone quickly snapped him out of it. “W-well, I didn't... you didn't say anything about not wanting me to do that!”

“Ugh, fluid aside, that was so quick! I was barely getting started!”

Embarrassed now, Dib shrank back in the chair. “Well, you were really hot, okay? And you had me so wound up already, and it was my first time, everything felt so good I just...” He gestured vaguely and then covered his face, groaning. “It's not my fault.”

“Whatever. Sit there like a good human and let me finish, then.” Zim tried to climb back onto him and Dib jumped, wincing at how sensitive he was now and not really in a good way.

“Zim, wait...”

“Is your spike supposed to have gone limp? No matter, I can probably just...” Zim lifted him and tried to slide back on, but Dib grabbed him and pushed him back.

“Hold on, you can't... I'm done,” he said.

“What do you mean, you're done?”

“I already came, I can't just...” Dib wasn't sure how to explain this. “I need some time. To recover, before I can get hard again. You trying to just hop on me like this hurts.”

“What?! Oh, that's ridiculous, I need more!”

“I know, I'm sorry, but we can't do it like this. Here, uh...” Dib got up, lifting Zim with him and turning around to sit him in the chair. Dib took a few moments to tuck himself away and pull his pants up, groaning at the mess, but he'll just have to deal with it later. “Why don't I do this for you?” He got down on his knees.

“Hm?” Zim leaned back in the chair, finding that Dib had left his coat laying in it and curiously moving his arms through the sleeves just to appreciate how nice and warm the material was. “What are- oh!” He arched when Dib's mouth pressed against his entrance, kissing slowly. “Oh that's disgusting, nngh...” He settled his hands into Dib's hair and flung his ankles over the other's shoulders. “Don't stop.”

Dib wasn't completely sure how to do this but he wanted to make sure he got Zim off, feeling bad about his premature finish. He hadn't meant to but he really had been overwhelmed by everything and Zim had felt so perfect around him... it had just happened. But he could do this for him. He grimaced a little as he tasted himself on Zim's skin, but tried to put it out of mind, instead thinking about how sweet Zim's skin was. He lapped curiously against his outer folds for a while, trying to see what was the most sensitive, soon finding that Zim moaned louder whenever he pressed up toward the base of his cock. It seemed to have a sheath up here it could slide back into, but it certainly wasn't doing that right now. The length was currently squirming against his face and even moving its tip through his hair. He was going to be such a mess later.

He moved both hands up under Zim's knees to hold his legs apart, now exploring inside with his tongue. The other was so slick inside. His body flexed in small waves around him, pressing to his tongue, which he moved in deeper. He really hoped this still felt good, though judging from Zim's small whimpers and chirps over him, it did.

As he explored with his tongue, he kept using his lips to kiss the other's folds, and after a while he moved a hand to stroke Zim's length too. He could tell he wasn't as coordinated as he could be, but Zim still seemed to like it, shaking and rocking against him. He smelled so good, his noises so cute...

It took about a minute of going down on the other for Zim to finish. Zim whimpered as he did, claws gripping painfully tight into Dib's hair, and Dib felt a gush of fluid from his cock as well as a flood of it against his tongue, enough that it dripped down his chin and he ended up jerking away, coughing and wiping his face off.

“Hah, ah... wow,” Zim muttered quietly, slowly releasing Dib and flopping back in the chair. “That was... interesting.”

“Feel better now?” Dib asked, leaning back and fixing his hair. He sighed at the feel of goo all in it.

Zim smiled at him, the blush mostly gone from his skin now, though there were a few small patches of it left. He was quite sweaty from the exertion but there were no more trembles. “Oh yeah. I feel great.” He still had Dib's sleeves on his arms and even hugged himself with them, nuzzling slightly into the collar. Dib pulled him into a hug and he hugged him back, nuzzling his neck and up to his cheek.

This was nice. Things felt good between them. Peaceful and affectionate.

Then Zim was letting go and shrugging the coat off, getting it out from under him and then tossing it into Dib's face. “I'd say that was a successful experiment.”

“Yeah, guess so, but... I'm still sorry. You know, for finishing so soon.”

Zim waved a hand. “Whatever, things happen, I suppose I couldn't expect your stamina to be as great as mine. You'll simply have to make it up to me later!”

“Later?” Dib found his glasses on the console and put them back on, then gave Zim a hopeful look. “You want to do this again?”

“Of course! Heat lasts for many of your days! I would like to make use of your body again.”

“Okay, well... yeah, I'm down with that.” Dib rubbed his neck, starting to feel a bit chilly and awkward now. He pulled his coat on and kept looking at Zim, still laying back naked in the chair, looking quite content. Dib wanted to squeeze in there with him and snuggle up, but he doubted Zim would allow that. “So, should I go now, then?”

Zim gave a curt nod. “I have no more use of you at the moment. I'll let you know when my desires flare up again. For now...” He wiped some of the sweat from himself and got up, gathering his clothes into an arm. “I must go cleanse myself of your filth.”

“My filth, eh?” Dib asked. “What a rude thing to say about the guy who just made you feel so good.”

“Don't act like it's some big accomplishment, I'm sure any human could have done an adequate job. An irken would have been far more satisfying.”

“Maybe. But you didn't have any other human or an irken. You had me.” Dib leaned in to brush their lips together. “And you liked it.”

“Of course I liked it, mating is supposed to feel pleasant,” Zim retorted. “Don't think this means anything, Dib. I'm still gonna make you suffer when I conquer Earth.”

“Sure. You're totally gonna conquer Earth after all this time.”

“Don't mistake my patience for incompetence! Earth just requires a very careful approach. You'll see, one day you'll all bow down to the Irken Empire!”

“Right.” Dib got the feeling that Zim's usual attitude was coming right back now that the heat was relieved for a bit. So he decided to take his leave before things escalated. “I'm going home, then. I need to shower too.”

“Yes, good, you stink! Get out of here!” Zim gave him a rough push as he walked away, but Dib just laughed and shook his head.

Despite Zim seeming to be back to normal, Dib got the feeling that what just happened was going to lead to a shift in their relationship. He was nervous to see how things might change, but hopeful too. He had liked making Zim feel good and could tell Zim was greatly enjoying pleasuring him too. Maybe he was being too optimistic but he saw this as just the beginning of something wonderful.


End file.
